As a lithographic technique in a process for producing a semiconductor element, known are double patterning technique based on ArF-immersion lithography, EUV lithography, nano-imprinting lithography, and others. Such conventional lithographic techniques have various problems, such as an increase in costs, a hard spec in overlay, and a high target in throughput, which follow the shrinking of patterns.
Under such a situation, it is expected that a directed self-assembly (DSA) phenomenon is applied to lithography. A directed self-assembly phase is generated by thermal energy stabilization, which is a spontaneous behavior; thus, a pattern high in dimensional precision can be formed. In particular, a technique using a phase separation of a block-polymer makes it possible to form a periodic structure of units having a shape that may be of various types and each having a size of several nanometers to several hundreds of nanometers by a simple and easy coating and an annealing process. In accordance with the content ratio between individual blocks in the polymeric block copolymer, the microdomain structure thereof is varied into, for example, a spherical, columnar or lamellar form, and in accordance with the molecular weight thereof, the size is varied, so that holes, pillars, and line patterns that may have various dimensions can be formed.
In order to use DSA to form a desired pattern over a wide area, it is necessary to lay a guide layer for controlling the generation position of a directed self-assembly phase. As the guide layer, the following are known: a physical guide layer (grapho-epitaxy) having an irregularity structure wherein a microphase separation pattern is formed in fine concaves; and a chemical guide layer (chemical-epitaxy) formed as an underlying layer underneath a DSA material to control the formation position of a phase separation pattern in accordance with the surface state of this layer.
However, when the formation position or size of such a guide layer is out of a desired position or size, the generation position of a directed self-assembly phase is shifted to an undesired position, or is not formed, resulting in a problem that a desired pattern is not obtained.